A method for isolation of hundreds of milligrams of lolitrem B is reported. Lolitrem E, the most abundant of the minor lolitrems, was isolated from side fractions and its structure determined by mass spectrometry and one-and two-dimensional NMR techniques. Lolitrem E differs from lolitrem B in being an ether, rather than an acetal, derivative of lolitriol. Evidence is presented that the compound previously isolated by Gallagher and co-workers, and assigned the structure of lolitrem C, was in fact lolitrem E. Lolitrem E, which is not tremorgenic in mice, is proposed as a biosynthetic precursor of lolitrem B.

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A new lolitrem, lolitrem F (2), was isolated from endophyte-infected perennial ryegrass. Its structure was shown by mass spectrometry and one- and two-dimensional NMR spectroscopy to be a 31,35-cis-fused isomer of lolitrem B. Base-catalyzed epimerization of 2 and lolitrem B (1) afforded their 31-epimers (4 and 3, respectively). Comparison with spectral data for 1 and 31-epi-lolitrem B (3) established lolitrem F to be 35-epi-lolitrem B. Compounds 1, 2, and 4 were equally tremorgenic in a mouse bioassay, but 3 was nontremorgenic. Base-catalyzed exchange of H-31 was found to permit efficient incorporation of deuterium (and potentially, therefore, of tritium) into 1 and 3. Keywords: Acremonium lolii; Lolium perenne; endophyte; lolitrem; tremor; ryegrass staggers; neurotoxin; mycotoxin

A released suspension culture lignin (RSCL) from Norway spruce (Picea abies) was subjected to a detailed two-dimensional NMR study. It was found that the most informative techniques were homonuclear Hartmann-Hahn (HOHAHA) spectroscopy and 13C-decoupled -detected multiple quantum 1H-1 13 3C-correlation (HMQC) spectroscopy. While correlations from the side chains of most of the commonly proposed lignin structural units were observed, no resonances assignable to the noncyclic benzyl aryl ether or diarylpropane-1,3-diol substructures, which have previously been claimed to account for up to 20% of the interunit linkages in lignins, could be observed, suggesting that the relative importance of these units to the structure of lignin is somewhat questionable. The rotating-frame NOE experiment (ROESY) showed correlations attributable to intraunit magnetization transfer. From the ROESY data, and by consideration of molecular modeling results, it was concluded that in the predominant (3-aryl ether interunit linkage most of the side chains were in the gauche conformation, with some in an anti conformation.

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